Law enforcement seizures of marijuana and methamphetamine fell significantly during the first months of the coronavirus stay-at-home orders in the U.S., then dramatically rebounded to levels even higher than before the pandemic, according to research released Tuesday. 

Cocaine, heroin and fentanyl seizures, meanwhile, remained relatively steady during March and April 2020, according to the paper published in Drug and Alcohol Dependence, which researchers said represents the first study to examine the effect of the pandemic on drug seizures. 

“These results give us a better idea regarding how availability of various drugs has shifted during the pandemic,” said lead author Joseph J. Palamar, a professor at New York University’s Grossman School of Medicine. “It’s important to know how drug use practices have changed during COVID.” 

Palamar and his co-authors also found that seizures of fentanyl, a synthetic opiate with high overdose risk that’s often mixed with other opioids like heroin, have increased steadily over the past two years. Fentanyl and other synthetic opiates killed over 36,000 Americans in 2019 — more than prescription opioids and heroin combined, according to the National Institutes of Health. 

“Results suggest that fentanyl availability continues to increase, perhaps independently of the pandemic,” said Palamar. “This is alarming — especially considering a lot of people who use drugs are exposed to fentanyl unintentionally as an adulterant.”  

People who use drugs should test them using fentanyl test strips in order to reduce risk, Palamar said. 

The researchers based their work on data from about 30,000 drug seizures from five U.S. regions that the Drug Enforcement Administration designates as “High Intensity Drug Trafficking Areas” — Chicago, Ohio, New Mexico, North Florida and the Baltimore-Washington metropolitan area. The data covered March 2019 to September 2020, allowing the researchers to observe pre-pandemic trends, the shock of initial lockdowns and gradual reopenings during the summer of 2020. 

The researchers noted, though, that drug seizures are an imperfect metric of overall drug use because they could indicate decreased or increased law enforcement activity rather than changes in smuggling. 

“Seizures don’t necessarily reflect use in the population,” said Palamar. “Although seizures do give us an idea about drug availability.”

One upside for researchers is that law enforcement agencies test the drugs they seize, according to Palamar. 

“Drugs seized are tested for their contents, so we know what these drugs actually contained,” he said. “Self-reported use is less reliable as people don’t always know what drug they actually used. For example, fentanyl is now commonly added to heroin and ‘bath salts’ are commonly added to ecstasy.”

Of all the seizures in the year-and-a-half examined by the researchers, 31% were of marijuana, 23% were of cocaine, 22% were of methamphetamine, 17% were of heroin and 7% were of fentanyl.

Palamar wrote the paper alongside Austin Lee of NYU, Thomas H. Carr of the University of Baltimore and Linda B. Cottler of the University of Florida. 

More than a year into the pandemic, researchers are only beginning to understand the effects of coronavirus-related policies on mental and physical health. Some researchers have linked the coronavirus and related lockdowns to increased depression, anxiety and domestic violence. 

Palamar said that the coronavirus has probably changed drug use patterns in the U.S., and that researchers need to examine the issue more closely in the future. 

“It’s important to know how drug use practices have changed during COVID,” he said.  “I’m worried that more people are using drugs with unknown contents and/or are using alone — without having anyone around to help if something goes wrong.”

While the literature around drug use and the pandemic is relatively small, one study by researchers at Dalhousie University in Canada found that people who did not frequently smoke marijuana before the pandemic decreased their use when initial restrictions were put in place, while people who were already frequent users increased their use even more. 

The United Nations Office on Drugs and Crime, meanwhile, has found that drugs like heroin, ecstasy, cocaine and methamphetamine were less available in Europe and North America during the early months of the pandemic. 

Palamar emphasized that he is not advocating for a particular policy response to drug usage by studying seizure trends.

“Seizure data trends have rarely been examined and these data are helpful in describing the drug landscape,” he said. “It should also be noted that I am by no means promoting drug arrests by analyzing these data, but rather utilizing a new source of data to provide the public with important and timely public health information.” 

The paper, titled “Shifts in drug seizures in the United States during the COVID-19 pandemic,” is forthcoming in Drug and Alcohol Dependence. Its authors are Joseph J. Palamar and Austin Lee of New York University, Thomas H. Carr of the University of Baltimore and Linda B. Cottler of the University of Florida. Palamar was lead author.